Garra makiensis (Boulenger, 1903)

Englmaier, Gernot K., Rodriguez, Nuria Vinuela, Waidbacher, Herwig, Palandacic, Anja, Tesfaye, Genanaw, Gessl, Wolfgang & Meulenbroek, Paul, 2020, New data on Garra makiensis (Cyprinidae, Labeoinae) from the Awash River (Ethiopia) with remarks on its relationships to congeners on the Arabian Peninsula, ZooKeys 984, pp. 133-163 : 133

Garra makiensis (Boulenger, 1903) Figures 4 , 5 , 6 , 7 , 8 , 9

Discognathus makiensis Boulenger, 1903:330 (type locality: Maki [Meki] River, Ethiopia), Fig. 4A

Discognathus rothschildi Pellegrin, 1905:291 (type locality: Gotta [Gota] River, Ethiopia), Fig. 4B

Material examined.

Comparative material from the Awash River drainage (including the Gotta River sub-drainage) is listed in Table 1 .

Identification.

See Figs 5 - 8 for general appearance of G. makiensis from the Awash River; Fig. 7 for tubercles on head; Fig. 8 for scales on chest and shape of gular disc; and Fig. 9 for axial skeleton and shape of supraneural bones. Tubercles on scales and the pectoral fin, and scale pattern on ventral side are shown in Suppl. material 2: Figs S1, S2. Measurements and counts are given in Tables 3 , 4 .

Longest examined specimen 147.9 mm SL (female, NMW 99504). Body elongated, moderately compressed, more in the caudal region. Shape of body and head very variable. Dorsal head profile slightly convex, its transition to back usually smooth, in few specimens with a slight nuchal hump. In most specimens, predorsal back outline rises gently, slightly convex or straight, to dorsal-fin origin. Postdorsal profile slightly concave to caudal-fin origin. Caudal peduncle almost twice as long as its minimal depth. The vent is close to the anal-fin origin (7.3-19.7 % of pelvic - anal distance). Head usually as long as body depth at dorsal-fin origin. Head depth at nape shorter than head length. Snout blunt and longer than orbit - operculum distance. Transverse groove weakly developed (absent in some specimens); transverse lobe separated from lateral field by a shallow groove (or without groove). Two deep grooves originating above anterior barbel, posteriorly not connected; at posterior end of upper groove a patch of few tubercles in some specimens (Fig. 7 ).

Tubercles on snout and head in both males and females (smallest specimen with tubercles: 45.4 mm SL, Awash River, S14), but often completely absent or rudimentary developed (Figs 6 , 7 ). Transverse lobe with large conical tubercles; tubercles extending to lateral surface and the area between anterior rim of eyes and nostrils. Depressed rostral margin usually without tubercles; in some specimens few and irregularly placed. Anterior extremity of the ethmoid field often elevated from depressed rostral surface and covered with large tubercles, especially in anterior region. Small tubercles are commonly spread on the frontal and occipital regions, sometimes extending to the operculum (Fig. 7 and Suppl. material 2: Fig. S1). In few specimens (n = 7), small circular tubercles on scales in the predorsal region and the lateral side of the abdominal region (above lateral line). A single specimen (NMW 99231, male, 91.2 mm SL, Awash River, S10) with tubercles on dorsal side of the pectoral fins (at fin membranes) (Suppl. material 2: Fig. S1).

Gular disc well-developed but often variable in size and shape (Fig. 8 ). Its width greater than its length. Width of torus less than disc length. Pulvinus wider than long and with few papillae. Labrum well-developed and longer than torus. Width of mouth usually less than snout length. Abundant papillae on rostral cap, torus, labellum and labrum. Rostral cap with invecked ventral margin. Two pairs of barbels, their length usually shorter than eye diameter; anterior barbel slightly longer or about equal to posterior barbel.

Dorsal fin with 3 or 4, commonly 4, unbranched and 8 branched rays, its last unbranched ray is the longest (89.0 % of dorsal-fin depth); length of first branched ray 86.4 % of dorsal-fin depth; second branched ray much shorter (76.9 % of dorsal-fin depth). Pelvic fin with a single unbranched ray and 7-9, commonly 8, branched rays; pelvic splint present. Long axillary scale at base of pelvic fin, its length 18.8-35.5 % of pelvic-fin length. Pectoral fin with a single unbranched ray and 13-17, commonly 16, branched rays. Caudal fin forked with 2+17 principal rays. Upper procurrent rays 7 (9), 8 (49) or 9 (3), lower procurrent rays 6 (14), 7 (42) or 8 (6).

Lateral line complete and going along midline. Total lateral-series with 37-40, commonly 38, scales. Lateral-series scales to posterior margin of hypurals 35-39, commonly 36. Transversal scale rows between lateral line and dorsal-fin origin 4 or 5, commonly 5; and 4-6, commonly 5 between lateral line and anal-fin origin. Chest, belly, postpelvic and predorsal regions fully scaled. Scales on chest usually deeply embedded (Fig. 8 and Suppl. material 2: Fig. S2); predorsal scales irregularly arranged. Between anal-fin origin and anus 0 (1) 1 (16) or 2 (42) scales; and 6 (6), 7 (24), 8 (22) or 9 (3) scales in postpelvic region. Circumpeduncular scale rows 16.

Total vertebrae 35-39, commonly 37; with abdominal vertebrae 20-22; predorsal abdominal vertebrae 9-12; caudal vertebrae 14-17; and 11-14 vertebrae between first pterygiophores of dorsal and anal fins. Most frequent vertebral formulae 21+16 (19, n = 74). Supraneural bones 3-5 (commonly 4 (16) or 5 (10), n = 27), first two square shaped and last two to three in front of dorsal fin elongated and largest (Fig. 8 ).

Morphological variability.

Similar to other Garra species in Africa and the Arabian Peninsula ( Krupp 1983; Golubtsov et al. 2012; Englmaier 2018), we found considerable morphological variability in G. makiensis (Fig. 6 ). Based on our data, we cannot confirm the presence of a sexual dimorphism, but the largest specimens were females (> 140 mm SL), and more males with prominent tuberculation on snout and head were found. Though few specimens were examined, and samples were collected during dry season only, our data suggest that body shape and tuberculation in G. makiensis might be (directly or indirectly) related to abiotic habitat characteristics. Specimens with a more slender body shape and without (or reduced) tubercles on snout and head (Fig. 6B ) were caught in low flow velocity habitats, whereas deep bodied specimens with large conical tubercles on snout and head (Fig. 6C ) exclusively occurred in high flow velocity habitats over coarse substrate. Intermediate morphs (Fig. 6A ) and large growing specimens with reduced tubercles (Fig. 6D ) were occasionally found.

Colouration.

In life (Fig. 5 ): Body colour usually light grey, above lateral line often pale-brown or blueish iridescent and darker than below. Head yellowish brown, mouth and ventral side cream. Iris white and yellow. Some individuals show an indistinct, roundish, dark blotch at posteriormost caudal peduncle. At anteriormost lateral line (behind upper edge of operculum) a small dark (rarely blueish iridescent, never red) blotch, not extending on gill cover. Fin membranes usually hyaline, sometimes light grey or yellowish; on caudal fin often light orange. Fin rays hyaline or pale. Dorsal fin with four to six indistinct black blotches at base of branched rays (strongest between 3rd and 6th branched rays).

In formalin (initial fixation) and later transferred to 75 % ethanol (Figs 6 - 8 ): Specimens usually light to dark grey, sometimes cream or brownish; darker above lateral line; ventral side cream to yellowish or orange. Back usually dark greyish; head brownish grey. Dark mid-lateral stripe usually of increasing intensity at caudal peduncle, often forming an indistinct blotch at posteriormost caudal peduncle. Fins pale, anterior part of caudal-fin base brownish. Indistinct black blotches at base of branched dorsal-fin rays (strongest between 3rd and 6th branched rays).

Habitat.

Garra makiensis was sampled from the mainstem Awash River and its tributaries (Mille River (T1), Borkana River (T3) and Jara River (T4)) (Figs 1 , 10 and Suppl. material 1: Table S1). The altitude ranged from 1,608 m a.s.l. (8°23'16"N, 38°54'30"E, S6) to 338 m a.s.l. (11°30'50"N, 41°38'51"E, S16). Specimens were collected from shoreline habitats, deeper stretches of the main channel, side channels, stagnant water bodies of the floodplains and lacustrine habitats (e.g., lakes Yardi and Gamari, Koka Reservoir); both low-flow and high-flow velocity habitats were inhabited. Substrate composition ranged from silt and sand to coarse stony substrate. The water was usually turbid (suspended solids); water temperature ranged from 21.1 °C to 31.9 °C; conductivity was between 286.7-1,710.3 μS cm-1; and dissolved oxygen was close to saturation (65.1-124.1 %) ( Englmaier et al. 2020b).

Distribution.

Garra makiensis is endemic to Ethiopia where it is found in endorheic drainages (Awash (including the Gotta River sub-drainage) and Meki) of the Northern and Central MER (Fig. 1 ) ( Golubtsov et al. 2002). It is absent from the headwaters and was found characteristic for the middle and lower sections of the Awash River ( Englmaier et al. 2020b). In the current study, we cannot confirm the presence of G. makiensis in the Meki River, its type locality. The Meki drainage is highly altered by human impacts (e.g., water abstraction, sand mining) and the last records of G. makiensis in this drainage date back to 1984 ( Golubtsov et al. 2002). The extended distribution range reported by Stiassny and Getahun (2007), including the southern part of the MER, the Blue and White Nile drainages and the Omo River drainage, contains uncertainty and needs clarification ( Wakjira and Getahun 2017).

Figures

Figure 1. Map of the study area in the Northern and Central Main Ethiopian Rift (NMER, CMER) showing sampling sites and examined material; thick lines denoting Main Rift faults, dashed lines showing transversal faults (Bonini et al. 2005). Study sites: S 1 - S 6 and T 1 - T 8 Awash River drainage, G 1 Gotta River (type locality of G. rothschildi), M 1 Meki River (type locality of G. makiensis), Z 1 - Z 2 Lake Ziway, and L 1 Lake Langano. Sampling sites in red showing localities where G. makiensis is known from examined material or was recorded during recent surveys. The small inserted map showing known distribution range of G. makiensis in the Awash and Meki River drainages.

Figure 4. General appearance of Garra makiensis. A BMNH 1905.7.25.87, lectotype of G. makiensis, female, 67.1 mm SL, Maki [Meki] River, Ethiopia, The Trustees of the Natural History Museum, London, B MNHN- 1905 - 0246, syntype of G. rothschildi, 135.3 mm SL, Gotta [Gota] River, Ethiopia, The Museum national d'Histoire naturelle, Paris.

Figure 5. Garra makiensis, alive, NMW 99224, 52.0 mm SL, Awash River at Lafessa (S 6). Photograph by W. Graf.

Figure 6. General appearance and morphological variability of Garra makiensis from the Awash River. A NMW 99485, female, 85.8 mm SL, Adayitu (S 13), B NMW 99485, female, 82.2 mm SL, Adayitu (S 13), C NMW 99491, male, 106.1 mm SL, Dubti (S 14), D NMW 99504, female, 147.9 mm SL, Jara River (T 3).

Figure 7. Lateral and dorsal view of head, in Garra makiensis from the Awash River. A and D same specimen as in Fig. 6 B, B and E same specimen as in Fig. 6 C, C and F same specimen as in Fig. 6 D.

Figure 8. Ventral view of head, in Garra makiensis from the Awash River. A same specimen as in Fig. 6 B, B same specimen as in Fig. 6 C, C same specimen as in Fig. 6 D.

Figure 9. Axial skeletons and supraneural bones in Garra makiensis. A NMW 99223, 56.0 mm SL, Awash River at Wonji (S 7), 10 showing last predorsal abdominal vertebra and 21 last abdominal vertebra, total vertebrae 36: 21 + 15, B lectotype of G. makiensis, same specimen as in Fig. 4 A, 10 showing last predorsal abdominal vertebra and 20 last abdominal vertebra, total vertebrae 36: 20 + 16, The Trustees of the Natural History Museum, London, C syntype of G. rothschildi, same specimens as in Fig. 4 B, 10 showing last predorsal abdominal vertebra and 21 last abdominal vertebra, total vertebrae 37: 21 + 16, The Museum national d'Histoire naturelle, Paris. Arrows showing position and numbers of preanal caudal vertebrae.

Figure 10. Habitat of Garra makiensis in the Awash River drainage and sampling site in the Lower Meki River where G. makiensis was absent. A Awash River at Lafessa (S 6, 1,608 m a. s. l.), B Awash River at Yimre (S 10, 797 m a. s. l.), C Middle Borkana River (T 3, 1,417 m a. s. l.), D Lower Meki River, upstream of Meki town (1,663 m a. s. l.).